The present invention relates to maskless exposure that forms a pattern on a photosensitive agent applied substrate and manufactures highly integrated devices. The present invention is applicable to manufacturing of a semiconductor device (such as an IC), an imaging device (such as a CCD), a communication device (such as an optical waveguide, and a magnetic head.
A projection exposure apparatus has been conventionally used to expose a mask pattern onto a substrate on which a photosensitive agent is applied, so as to manufacture a semiconductor device, a liquid crystal panel, and the like. However, as finer processing to the mask pattern and larger mask sizes are demanded with the improved integration and increased area of the device, an increase of the mask cost becomes problematic. Accordingly, the maskless exposure that dispenses with the mask for exposure has called attentions.
One exemplary, attractive maskless exposure is a method for projecting a pattern image onto a substrate using a phase-modulation type spatial light modulator (“SLM”). The SLM is a parallel-connected type device, and the number of pixels per unit time may possibly be increased enormously. In particular, a so-called deformable mirror device (“DMD”) type SLM that changes a surface shape of a reflector, modulates the light, and is suitable for an exposure apparatus, because the DMD provides a high contrast, works at a relatively short wavelength, and is stable to the environment. The phase modulation manner needs a minute displacement of a mirror, such as about a quarter of the wavelength of the light, and works at a high speed. Prior art of the phase-modulation type SLM include U.S. Pat. Nos. 5,841,579, 5,486,851, 5,311,360 and 6,133,986, Japanese Patent Application, Publication No. 6-102459.
Disadvantageously, the conventional maskless exposure that utilizes the phase-modulation type SLM has difficulties in providing a high throughput and a high resolution with a simple structure. For example, use of a diffraction grating type modulation pattern called a grating light valve (“GLV”) makes complex the SLM's structure. See U.S. Pat. Nos. 5,841,579 and 5,311,360.
A large Schlieren optics is needed to convert a light phase pattern into a light intensity pattern and project the light intensity pattern onto the substrate (U.S. Pat. Nos. 5,486,851 and 6,133,986), but use of the Schlieren optics makes complex the optical system. In addition, a fine lens array is needed in addition to the Schlieren optics (U.S. Pat. No. 6,133,986), and it is difficult to manufacture and mount the fine lens array having excellent imaging performance with small aberrations and dispersions.